Consider the function f(x, y, z) = 4 - x2 - y2 - 22, (a) Find the domain of the function. (b) Find the directional derivative of of the function at the point (0, 1, 1) in the direction u = (c) Suppose that w = f(x, y, z), where x = sin(uu), y = cos u, z = e. Find du Show your work in your uploaded file